Flowering in plants is a consequence of the transition of the shoot apical meristems from vegetative to reproductive growth in response to environmental and internal signals. Currently, there is little information about the regulation of flowering time in maize. Id1 gene (indeterminate 1) is the only maize cloned gene with a clear role in the floral transition (Colasanti et al., (1998) Cell. 93:593-603). The Id1 gene encodes a transcription factor and regulates the production of a transmissible signal in the immature leaves that induces the transition of the shoot apical meristems from vegetative to reproductive development.
Flowering time determines maturity and that is an important agronomic trait. Genes that control the transition from vegetative to reproductive growth are essential for manipulation of flowering time. Flowering genes will provide opportunities for enhanced crop yield, adaptation of germplasm to different climatic zones, and synchronous flowering for hybrid seed production. Developing early-flowering inbred lines will facilitate the movement of elite germplasm across maturity zones. Flowering genes also provide an opportunity for engineering vernalized corn, enabling fall planting and over-wintering. Vernalization may be achieved by the over expression of the activator of flowering or the down-regulation of repressors of flowering in transgenic plants.